Gasoholics Anonymous

Why Bikes Are a Sustainable Wonder goes over some aspect of bicycling which are very positive. Riding a bicycle uses minuscule amounts of energy compared to any other form of transportation. Riding a bicycle gives exercise and promotes better health. Bicycling uses less land area, leaving more land available for other things such as houses or farms.

Searching eBay for "folding bicycles" turns up lots of options.

Foldabikes carries the Brompton bicycle. They also have travel pages extolling the possibility of using a folding bicycle for long distance travel.

West Marine carries a range of folding bicycles, because, well, that would be helpful for a boat owner. For similar reasons RvToyOutlet also has folding bicycles.